title: Monooxygenase, a novel beta-cypermethrin degrading enzyme from Streptomyces sp.
abstract: The widely used insecticide beta-cypermethrin has become a public concern because of its environmental contamination and toxic effects on mammals. In this study, a novel beta-cypermethrin degrading enzyme designated as CMO was purified to apparent homogeneity from a Streptomyces sp. isolate capable of utilizing beta-cypermethrin as a growth substrate. The native enzyme showed a monomeric structure with a molecular mass of 41 kDa and pI of 5.4. The enzyme exhibited the maximal activity at pH 7.5 and 30°C. It was fairly stable in the pH range from 6.5-8.5 and at temperatures below 10°C. The enzyme activity was significantly stimulated by Fe(2+), but strongly inhibited by Ag(+), Al(3+), and Cu(2+). The enzyme catalyzed the degradation of beta-cypermethrin to form five products via hydroxylation and diaryl cleavage. A novel beta-cypermethrin detoxification pathway was proposed based on analysis of these products. The purified enzyme was identified as a monooxygenase by matrix-assisted laser desorption/ionization time-of-flight/time-of-flight mass spectrometry analysis (MALDI-TOF-MS) and N-terminal protein sequencing. Given that all the characterized pyrethroid-degrading enzymes are the members of hydrolase family, CMO represents the first pyrethroid-degrading monooxygenase identified from environmental microorganisms. Taken together, our findings depict a novel pyrethroid degradation mechanism and indicate that the purified enzyme may be a promising candidate for detoxification of beta-cypermethrin and environmental protection.
authors.affiliation: College of Natural Resources and Environment, South China Agricultural University, Guangzhou, People's Republic of China.
authors.forename: Shaohua
authors.initials: S
authors.lastname: Chen
authors.forename: Qingsheng
authors.initials: Q
authors.lastname: Lin
authors.forename: Ying
authors.initials: Y
authors.lastname: Xiao
authors.forename: Yinyue
authors.initials: Y
authors.lastname: Deng
authors.forename: Changqing
authors.initials: C
authors.lastname: Chang
authors.forename: Guohua
authors.initials: G
authors.lastname: Zhong
authors.forename: Meiying
authors.initials: M
authors.lastname: Hu
authors.forename: Lian-Hui
authors.initials: LH
authors.lastname: Zhang
mesh_terms: D001483:Base Sequence; D004787:Environmental Pollution / Q000517:prevention & control*; D006863:Hydrogen-Ion Concentration; D007306:Insecticides / Q000378:metabolism*; D019216:Metals, Heavy / Q000494:pharmacology; D006899:Mixed Function Oxygenases / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011722:Pyrethrins / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013302:Streptomyces / Q000201:enzymology*; D013696:Temperature
chemical_list: D007306:Insecticides; D019216:Metals, Heavy; D011722:Pyrethrins; C017160:cypermethrin; D006899:Mixed Function Oxygenases